Dental laser for the treatment of soft tissue

ABSTRACT

A dental laser comprises a hand piece ( 100 ) having a grip region ( 100   a ) and a treatment tip ( 101 ) with an outlet point ( 101   a ), arranged at a distal end, for laser light ( 102 ), and further comprises a light source ( 103 ) and light conduction means ( 105 ) for providing laser light ( 102 ) at the outlet point ( 101   a ). The laser light ( 102 ) has a wavelength ( 104 ) of 445±20 nm, in particular, 445±10 nm and more particularly 445±5 nm, and an optical power output is provided at the outlet point in a power range of at least 2 W, advantageously at least 3 W and, in particular, 3.5 W. In another dental laser the laser light ( 102 ) has a wavelength ( 104 ) of 410±10 nm, and an optical power output is provided at the outlet point ( 101   a ) in a power range of no less than 1 W to no more than 2 W.

TECHNICAL FIELD

The invention relates to a dental laser that is designed for thetreatment of soft tissue and that comprises a handpiece having anapplication tip for emitting the laser light. In dentistry the softtissue, in particular, the gum is cut with a dental laser, which hasmore power than a dental laser for disinfecting periodontal pockets orroot canals.

PRIOR ART

The prior art discloses the use of dental lasers that are designed tocut soft tissue and that use laser light in the infrared range. Typicalwavelengths of such laser light are 810±15 nm, 940 nm or 975±15 nm. Inthis case the laser beams are introduced into an optical waveguide ofthe application tip; and the distal end of the optical waveguide isbrought into contact with the soft tissue. In order to cut the softtissue, power levels in a range of 2 to 6 W are used at the distal endof the application tip, so that the result is intense heating of thetissue not only in the actual operating area, but also in the adjacenttissue.

Furthermore, it is also known to use diode lasers for other dentalapplications. For example, WO 2009/003014 A2 discloses a plurality ofdental lasers, for example, a diode laser, which is provided for thetreatment of soft tissue with a large coagulation zone for betterhomeostasis and which has a wavelength in the range of 500 to 1,350 nmand a power output of 1 to 100 W. Another dental laser, which is knownfrom WO 2009/003014 A2 and which is provided for the treatment of softtissue with a minimum zone of effectiveness and precise tissue cutting,has wavelengths of 300 to 450 nm or 1,350 to 3,000 nm and a power outputof 0.1 to 100 W. The published document WO 2009/003014 A2 discloses yetanother dental laser, which has several wavelengths of 410 nm, 577 nm,975 nm, 1,470 nm, 1,890 nm and 2,940 nm; and these wavelengths matchdifferent maxima of the blood absorption and the water absorption, withthe water considered to be the main absorber in the soft tissue of themouth. The laser beams exit the handpiece through a tip. Although it isknown from other lasers for cutting hard dental tissue, such as Er:YAG,Er:YSGG, that liquid is supplied for cooling or for facilitating theprocess, cooling the preparation site with water is always ruled out,when the wavelength that is employed is especially well absorbed bywater. Therefore, in the case of diode lasers, in which the wavelengthsthat are used have a high water absorption, no cooling is provided.

All of the dental diode lasers known to date are operated in theso-called “contact mode”, which means that the application fiber is indirect contact with, i.e., touches, the tissue that is to be cut. Inthis case the cutting of the tissue is carried out mainly by means ofthe thermal effect of the application fiber. The high temperature, whichis required at the application fiber for the cutting, is achieved, onthe one hand, by providing a sufficient laser power output and, on theother hand, by conditioning the application fiber prior to treatment.The fiber can be conditioned, for example, by blackening the surface ofthe fiber, for example, by means of paper. For this purpose, the fiberand the paper are brought into direct contact; and the laser isactivated. The now blackened surface of the application fiber absorbsmore light from the laser source and; as a result, the fiber is heatedup with a higher degree of intensity.

The cutting of the tissue is also facilitated by the absorption of thelaser radiation, issuing from the application fiber, in the tissue. Thisabsorption depends, among other things, on the wavelength of the laserlight. Thus, it has been found that at a wavelength of 940 nm, there isbetter absorption of the laser radiation in the soft tissue than at 970nm.

In principle, cutting in contact mode always entails that a large amountof heat will be introduced into the tissue. On the one hand, this heatinput is necessary for cutting, but, on the other hand, may also lead tothermal degradation or at least high stress on the tissue itself and/orthe surrounding structures; in this case bone structures are also meant.Nevertheless, no dental diode lasers are known that operate in thecontactless mode.

SUMMARY OF THE INVENTION

A dental laser of the invention comprises a handpiece having a gripregion and a treatment tip with an outlet point, arranged at a distalend, for laser light and, furthermore, comprises a light conductionmeans, arranged in the handpiece, for providing laser light at theoutlet point, with said laser light coming from a light source, arrangedinside or outside the handpiece. The laser light has a wavelength of445±20 nm, in particular, 445±10 nm and more particularly 445±5 nm, andthe optical power output is provided at the outlet point in a powerrange of no less than 2 W to no more than 5 W, advantageously at least 3W and, in particular, 3.5 W.

At optical power output levels in a range starting at 2 W and, inparticular, at 3.5 W, there is the possibility of operating the laser ina contactless mode at good to very good cutting efficiency withsignificantly less thermal degradation, since the absorption of 445 nmdirectly in the tissue is better. At 445 nm the absorption in the tissuetakes place in the hemoglobin by orders of magnitude more readily thanin water. At other wavelengths, such as 808 nm, 810 nm, 940 nm, 970 nm,980 nm, the absorption curves of water and hemoglobin are closertogether by powers of ten.

The thermal degradation is minimized, in particular, by the fact thatthe heat input by the heated application fiber itself is absent and onlycontributes heat owing to the absorption of the laser radiation in thetissue in order to heat the tissue. Five watts are considered to be theupper limit to ensure a sufficient distance from a power output levelthat will damage the soft tissue.

Due to the fact that, when cutting, the heat input by the heatedapplication fiber itself is absent and that the tissue to be cut has avery high water content, water that does not evaporate directly as inthe case of other wavelengths, such as 808 nm, 810 nm, 940 nm, 970 nm,980 nm, can leave the tissue during the cutting process. Since waterabsorbs light having a wavelength of 445 nm very sparingly, the water isnot appreciably heated or vaporized by the laser radiation. As a result,the exiting tissue fluid itself also cools the preparation site.

Since the fiber does not make contact with the preparation site and theabsorption of the laser light in water is very low, it is also possibleto use external water cooling for the cutting site in such a way thatjust the treatment instrument alone causes evaporation, i.e., a decreasein the cooling capacity. In the case of external cooling the coolingmedium, such as, for example, water, can be fed to the application fiberat the proximal end of the application fiber and from there can flow,for example, due to gravity, to the distal end of the application fiber.However, it is also possible to feed, starting from the handpiece, thesmallest possible amounts in a pulsating manner in the direction of thedistal end of the application fiber by means of pressure and, in sodoing, to form fine droplets.

Thus, the soft tissue can be cut particularly well, efficiently andgently at a wavelength of 445 nm and an optical power output in therange starting from 2 W and, in particular, at 3.5 W.

The optical power output at the outlet point can be advantageouslychangeable to a different power range, with the different power rangerunning from at least 1 W to less than 2 W. At low laser power levelsranging from 1 to 2 W, the dental laser can be used in contact mode.

Based on the absorption mechanisms described above, the result is atherapeutic window that lends itself to the use of a blue diode laserhaving a laser power output in the range of 1 to 3.5 W and even higher.

Another subject matter of the present invention is a dental laser, asdescribed above, but in this case the laser light has a wavelength of410±10 nm, and an optical power output is provided at the output pointin a power range of no less than 1 W to no more than 2 W.

At this shorter wavelength the absorption behavior of the laser light inthe soft tissue is once again noticeably improved, so that a smallerpower output is sufficient. This feature may justify the possibly higherfinancial outlay associated with providing a light source for laserlight of this wavelength.

Advantageously the light source may comprise at least one laser diode,preferably at least two, and, in particular, three.

This aspect makes it possible to provide a handpiece that is compact andpermits easy handling.

The laser diodes can be located in a device that transmits the laserradiation to the handpiece by means of a light guide. However, it isalso possible to integrate the laser diode, required to generate thelight, or the necessary diodes directly into the handpiece.

Advantageously the light conduction means for providing laser light atthe outlet point may have application fibers between 150 and 350 μm indiameter.

The advantage of the fiber between 150 and 350 μm is that at thesediameters the power level is relatively high in relation to the exitsurface. The small diameter also enables small cutting widths,especially if the fiber is guided over the tissue to be cut withoutmaking contact, since the divergence of the radiation, which isprimarily a function of the material of the light guide, has to be takeninto account.

Advantageously a coolant line can be arranged in the handpiece; andthere may be an outlet opening, from which the coolant, directed to thepreparation site, issues. In this case the amount of coolant rangespreferably from 0.1 to 10 ml/min. The result of this output of thecooling medium is that not only is the preparation site cooled, but thetissue is also wetted in a targeted way, features that are beneficial tothe healing process. Too large a quantity of coolant attenuates thelaser power at the coolant in spite of the very low absorption; at 0.1ml/min. it is possible to ensure wetting.

Advantageously the coolant may have a disinfecting effect. This featuremakes it possible not only to cool, but also to disinfect thepreparation site.

In the present invention a dental laser is provided that can be used inthe surgical treatment of the human or animal body, and, as a result,the side effects are reduced; and it can be assumed that the wound willheal much faster.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail in the drawings. In thedrawings:

FIG. 1 shows a schematic diagram of an inventive dental laser with anoutlet point of the laser light from an application fiber;

FIG. 2 shows the dental laser from FIG. 1 with an outlet point of thelaser light in a free jet.

EXEMPLARY EMBODIMENT

FIG. 1 shows a dental laser with a handpiece 100 for the treatment ofthe human or animal body by means of laser beams 102. The laser beams102 are generated in a laser module 106 by means of one or more laserdiodes 103 with laser light of a wavelength 104 of 445±20 nm, preferably445±10 nm, in particular, preferably 445±5 nm and are transmitted to thehandpiece 100 by means of a light guide 108. The handpiece 100 has ahousing 101 with a grip region 100 a and a treatment tip 101 with anoutlet point 101 a, disposed at a distal end, for the laser light 102.

In the housing there is a light conduction means 105 for providing laserlight at the outlet point 103, with the laser light coming from a lightsource, arranged inside or outside the handpiece 100, in the form of oneor more laser diodes 103.

According to a preferred embodiment, three laser diodes, which arearranged in a laser module 106 separate from the handpiece 100 and whichhave a wavelength of 445 nm±20 nm, each having an optical power outputof 1.6 W, are coupled to a laser beam 102 and are guided in thehandpiece 100 by means of a light guide 108. The net result is a nominalpower output of 3×1.6 W=4.8 W. Owing to the losses inside the lasermodule 106, caused by the optical components, owing to the couplinglosses between the laser module 106 and the transfer fiber 108 to thehandpiece 100 as well as owing to the losses in the handpiece 100 itselfand during the coupling of the treatment tip 101, the power output thatremains available at the distal end of the treatment tip is only about3.5 W.

In the treatment tip there may be an application fiber, at the distalend of which the laser light exits. However, it is also possible todirect the laser light to the treatment site in a free jet without alight guide. This arrangement is shown in FIG. 2. Starting from thelight conduction means 105, a free laser beam 102 travels inside thehandpiece 100 and issues from the handpiece at an outlet point 101 aafter a beam deflection by means of an optical component 113, like amirror. Downstream of the light conduction means 105 means 114 may beprovided, for example, optical means, such as lenses, which lendthemselves to reducing the divergence of the laser radiation. In thisway it is possible to extend the necessary working distance from theoutlet point 101 a to the preparation site 112, so that the distance, atwhich it is easy to work, extends over an enlarged area.

If the nominal power output of each of the diodes is 4.8 W, then theelectric power output of the laser module is 17.2 W, i.e., 3×4.8 V×1.2A.

Moreover, it is possible to cool the preparation site with an externallysupplied cooling fluid. Water lends itself well to this task, but aphysiological saline solution would be just as suitable and would havethe advantage that it is readily available sterile.

The handpiece 100 may have a coolant line 109, through which a coolant110 may be fed to an outlet opening 111, where the coolant 110 exits insuch a way that it is directed to the preparation site 112.

The amount of coolant can be preferably between 0.1 and 10 ml/min. Thecooling can be carried out preferably by means of water or aphysiological saline solution.

With the use of the new wavelength, 445 nm, blue light, and theincreased optical laser power output it is possible to cut in thecontactless mode due to the absorption behavior of the soft tissue.

The blue light is not primarily absorbed by the water, but rather thehemoglobin, which is also in the tissue. At a wavelength of 445 nm, theabsorption coefficient for hemoglobin is 10⁵ times higher than theabsorption coefficient for water. This absorption behavior makes itpossible to cut, even without the thermal transmission of energy fromthe fiber to the tissue. The tissue is processed by just the energyalone that is generated in the tissue by the radiation.

The laser light, which is used for cutting, may also be provided due tothe fact that the laser diode sits directly in the handpiece and thatthe application fiber is coupled to the laser diode. The invention isindependent of the generation and transmission of the laser light.

In the case of a laser diode having, for example, a power output of 3.5W, this laser diode may be used directly in the handpiece. If the laserdiode is placed in the handpiece, the transmission losses are very low,since there is only one interface to the application fiber.

1. Dental laser, comprising a hand piece having a grip region and havinga treatment tip with an outlet point, arranged at a distal end, forlaser light; further comprising a light conduction means, arranged inthe handpiece, for providing laser light at the outlet point, with saidlaser light coming from a light source, arranged inside or outside thehandpiece, wherein the laser light has a wavelength of 445±20 nm, andthat an optical power output is provided at the outlet point in a powerrange of no less than 2 W to no more than 5 W.
 2. Dental laser, asclaimed in claim 1, wherein the optical power output at the outlet pointcan be changed to a different power range, with the different powerrange running from at least 1 W to less than 2 W.
 3. Dental laser,comprising a hand piece having a grip region and having a treatment tipwith an outlet point, arranged at a distal end, for laser light; furthercomprising a light conduction means, arranged in the handpiece, forproviding laser light at the outlet point, with said laser light comingfrom a light source, arranged inside or outside the handpiece, whereinthe laser light has a wavelength of 410±10 nm; and that an optical poweroutput is provided at the outlet point in a power range of no less than1 W to no more than 2 W.
 4. Dental laser, as claimed in claim 1, whereinthe light source comprises at least one laser diode.
 5. Dental laser, asclaimed in claim 1, wherein the treatment tip for providing laser lightat the outlet point has application fibers between 150 μm and 350 μm indiameter.
 6. Dental laser, as claimed in claim 1, wherein a coolant lineis arranged on or in the handpiece; and that there is an outlet opening,from which coolant exits in a directed manner, wherein the amount ofcooling ranges from 0.1 to 10 ml/min.
 7. Dental laser, as claimed inclaim 6, wherein the coolant has a disinfecting effect.
 8. Method forthe surgical treatment of the human or animal body with the aid of laserlight, using the dental laser of claim
 1. 9. Dental laser, as claimed inclaim 3, wherein the light source comprises at least one laser diode.10. Dental laser, as claimed in claim 3, wherein the treatment tip forproviding laser light at the outlet point has application fibers between150 μm and 350 μm in diameter.
 11. Dental laser, as claimed in claim 3,wherein a coolant line is arranged on or in the handpiece; and thatthere is an outlet opening, from which coolant exits in a directedmanner, wherein the amount of cooling ranges from 0.1 to 10 ml/min. 12.Dental laser, as claimed in claim 11, wherein the coolant has adisinfecting effect.
 13. Method for the surgical treatment of the humanor animal body with the aid of laser light, using the dental laser ofclaim 3.